Is Salt Unfairly Demonized?

Q. In a recent interview, you mentioned cutting back on added sugar as one of the most important things you can do to improve your diet. I noticed you didn’t mention the importance of limiting sodium. Do you think the concerns over sodium are over-blown?

A. In a word, yes. In the recently released 2010 Dietary Guide for Americans, they really came down hard on salt, stressing the need for all Americans to reduce their sodium intake. Given all the things about the typical American diet that could use fixing, I thought it was a little odd how much emphasis they put on this. (Obviously, the salt lobby was asleep at the switch during the hearings…)

The rationale for universal sodium restriction rests a string of loosely related statistics:

One in three American adults has high blood pressure–which is a major risk factor for stroke and death.

The risk of high blood pressure goes up parallel to salt intake.

Average intake of sodium is about 3500mg per day (Recommended intake is 2300mg for healthy individuals and 1500mg for those at risk.)

Based on this, the reasoning is that getting everyone to eat less salt will reduce the incidence of high blood pressure, thereby reducing strokes and death. But obviously, we’d be “treating” a lot of people who don’t need it in order to get at those who do. Even among those with high blood pressure, only about 60% are salt-sensitive. For the other 40%, reducing sodium does little to correct high blood pressure. (Black Americans are much more likely to be salt-sensitive.)

Where’s the Evidence?

So the question is, what benefit do the 66% of Americans with normal blood pressure get from restricting sodium? A commentary in the Journal of the American Medical Association argues that there have been no randomized clinical trials showing that reducing sodium reduces illness or death in otherwise healthy people. Observational studies on the relationship between sodium intake and health have been mixed. Some have found a relationship between high sodium intake and cardiovascular events; others found no relationship.

Furthermore, the JAMA commentators point out, it’s not true that restricting sodium does no harm. Reducing sodium enough to lower blood pressure has also been shown to reduce insulin sensitivity, for example.

Is Reducing Salt the Best Way to Beat High Blood Pressure?

Here are some more statistics to consider:

The risk of hypertension goes up steeply with age, even though sodium intake generally does not.

The risk of hypertension goes up with body weight, independent of salt intake.

Twice as many people are overweight as have high blood pressure.

The overweight are also at risk of many other diseases, including Type 2 diabetes.

In the grand scheme of things, it would save a lot more lives to get people to lose weight rather than focusing on salt reduction. In fact, losing weight may reduce blood pressure more reliably than cutting salt. (Reference.) But that sort of brings us full circle…because cutting back on sodium might indirectly lead to weight loss.

Benefits of Salt Reduction May Be Indirect

Whether or not the sodium itself is a problem, salty foods stimulate appetite and lead to overeating. (Here’s an interesting study on this.) Imagine sitting down with a bowl of raw unsalted almonds. Now imagine sitting down with a bowl of roasted salted nuts. Which bowl gets emptied more quickly?

About 70% percent of the sodium in the American diet comes from packaged and prepared foods–foods which contribute a disproportionate amount of calories and anti-nutrients like trans fats without providing much meaningful nutrition. Foods that are literally engineered to promote over-consumption. Foods that push other more nutritious foods out of the diet.

How Reducing Salt Could Improve Diets and Health

If hammering everyone to reduce sodium results in people eating less processed junk food and more fresh food, we win on several counts. Not only does it reduce sodium intake, but a diet of fresh foods will likely be higher in potassium, which helps lower blood pressure. It’s also likely to promote healthier body weight.

Who Needs to Worry About Sodium?

About 10 to 25% of the general population are sodium sensitive; for these, people consuming too much sodium may increase their risk of cardiovascular disease and death, even if they have normal blood pressure. But in the context of a diet of mostly fresh foods, I think most people have little to fear from the salt shaker.

Can we quantify “high salt diet”? Are we talking about 3400mg/day or something more? Are these links correlations or causal? Does salt produce these effects in the general population or in a subset, such as salt-sensitive or hypertensive? I think these are all questions we’d need to explore to determine what level of salt-restriction is really justified and in what population.

I agree that the negative effects of salt are likely to be higher among salt sensitive. However, as stated by Eric (below) reducing salt intake at the population level might be the best way to reduce salt intake on individual level because salt is so widely spread to food items.

These associations are not restricted to salt sensitive. Many of these associations are from prospective cohort studies where participants are classified according to the intake of salt. Data from Europe, Japan and US show how sodium is linked to cardiovascular outcomes. See for example He et al. (NHANES I, CV outcomes) http://jama.ama-assn.org/content/282/21/2027.long or Hu et al. (Finland, T2D) http://bit.ly/hxrLgM

If you do PubMed enquiries you will find wealth of human data on other risks I mentioned (perhaps this is not the right forum for extensive literature review).

Salt sensitivity is very interesting phenomenon. It is now postulated that high salt diet (the current 3400 mg or so) for a long time sensitizes many of us to salt. In other words, more salt you get more likely you are to become salt sensitive later in life.

Furthermore, people with high insulin levels possess decreased excretion of salt. In other words, prediabetics and type 2 diabetics have special problems in handling salt. (for example DeFronzo 1981). One could argue that all type 2 diabetics are salt sensitive.

And let’s also face this fact. The more industry uses salt, the more we consume sugary sodas and alcohol drinks. Majority of citizens are going to use processed food with high salt content no matter how much we dietitians advocate opposite (fresh food).

Cutting back salt seems to be well substantiated. Somehow this debate reminds me about what was going on with sugar and HFCS some years ago. Now, everybody seems to agree that sugar is no good for health. Was it so a decade ago? Broad negative effects of salt should be more widely discussed.

I appreciate your thoughts! Interesting that you note that people with high insulin levels have lowered sodium excretion in light of the observation (noted in my post) that salt reduction reduces insulin sensitivity.

Ultimately, it’s the second to last paragraph of your comment that resonates most with me. The foods that are contributing most of the salt would be better off eliminated! If people were eating a diet of fresh foods, the sodium content of their diets would go down and their potassium intake would go up. (I don’t think think the sodium/potassium balance has been adequately accounted for in most of these sodium studies.) Their taste buds would probably adjust to a lower salt preference. In that context, I feel that there’s little danger for most people in salting their food to taste.

I’m really late in the game, but I was researching this matter as a result of the new dietary guidelines for children’s hot lunches.

It seems that even the data analyses refers to mortality in people who already suffer from hypertension, obesity and/or metabolic syndrome.
For example, your first reference concludes “Our analysis indicates that high sodium intake is strongly and independently associated with an increased risk of cardiovascular disease and all-cause mortality in overweight persons.”

For healthy children and people with low to normal blood pressure, does this still apply? Due to my own low blood pressure, I was told to increase my salt intake…

I did hear one statistic being thrown around that sodium restriction drops blood pressure 2-6 mmHg. That’s insignificant and not enough to stop taking medication. For some, sodium restriction will cause blood pressure to rise. I will see if I can find the paper that statistic is from. I definitely agree that weight loss is a much better focus than sodium restriction.

A few more things to consider:
– risk of high blood pressure goes up with age.
– that includes risk of salt sensitive blood pressure going up with age.
– it gets harder to make one’s own food with age.
– it gets harder to read labels with age.
To me, the “is it more important to get the population to lose weight or get them to use less sodium?” is a no-brainer. It is more important to get the population to lose excess weight. BUT, sodium is lower hanging fruit. There have been many campaigns and efforts to get people to eat-less-move-more with little success. The low population-wide targets for sodium should lead to food industry pressure to lower sodium in many products making it ultimately easier for those who need to lower sodium — especially the elderly who are most affected and in greatest need of assistance.

And by the way, the salt lobby was most definitely NOT asleep at the switch at the hearings. E.g., at the initial release of the lower sodium recommendations, when the floor was opened to questions it was almost exclusively questions from salt lobbyists.

If Americans cut out most processed foods, then there wouldn’t be a need to worry about salt or sodium. I don’t worry very much about the salt I sprinkle when cooking or eating homemade meals. But I do worry about the sodium that’s in processed foods at the grocery and even worse, restaurants. Even “natural” processed foods can be filled with too much sodium!

Hi Monica, I was fascinated by your discussion of sodium, especially to learn of a connection between a low-sodium diet and insulin resistance. Have you read at what levels this might occur, how great the effect could be (or what might explain it)? Thanks.

The usual argument in favor of including salt in the diet centers on the idea that it won’t hurt you–not that it’s good for you. You don’t need any salt if you get your sodium by eating lots of vegetables. So I look at it this way–even IF salt isn’t bad for you (which I don’t believe), which is a healthier thing to eat – salt or vegetables?

I’m not sure which of Ms. Reinagel’s bad habits you are referring to – she probably has several. Are any of them related to salt? I’m not so sure. I mean, squeezing the toothpaste from the middle of the tube is objectionable, and can safely be called a “bad habit.” But, there is no clear connection to salt.

Since she advocates avoiding processed foods, that couldn’t be what you mean. She admitted, in a roundabout way, that she isn’t worried about sprinkling a little salt on her food at home.

I have to weigh in here with a personal story. When my son was 15 his BP was 140/100 even though his 4 brothers were normal and they were all athletic. We cut his sodium intake to less than 2000 mg/day and with no other diet changes his BP was down to 100/80 within 3 months. He has had to watch it ever since. It has been 9 years and the only factor that affects his BP is when his diet goes off course with sodium. He cut out all processed, (canned and frozen) foods and stopped the fast food stops. Fresh foods and a regular salt shaker and all is well. If everyone stopped buying processed crap and went back to mother nature, we would spend less time and money going to doctors.

There are many studies with conflicting evidence. In one study reducing salt causes a miniscule spike in blood pressure, in another it causing an increase. This is a politically subject with little conclusive evidence. Even articles that look at the Japanese do not attempt to determine if high blood pressure is caused by the Japanese lifestyle instead of salt. Here is a link to the article.

The first sentence in my above post should have read:
There are many studies with conflicting evidence. In one study reducing salt causes a miniscule spike in blood pressure, in another it causing a decrease.

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